Redundant Nerve Roots of the Cauda Equina: MR Findings

PURPOSE: To evaluate MR findings of redundant nerve roots (RNR) of the cauda equina. MATERIALS AND METHODS: 17 patients with RNR were studied; eight were men and nine were women, and their ages ranged from 46 to 82 (mean63) years. Diagnoses were established on the basis of T2-weighted sagittal and coronal MRI, which showed a tortuous or coiled configuration of the nerve roots of the cauda equina. MR findings were reviewed for location, magnitude, and signal intensity of redundant nerve roots, and the relationship between magnitude of redundancy and severity of lumbar spinal canal stenosis (LSCS) was evaluated. RESULTS: In all 17 patients, MR showed moderate or severe LSCS caused by herniation or bulging of an intervertebral disc, osteophyte from the vertebral body or facet joint, thickening of the ligamentum flavum, degenerative spondylolisthesis, or a combination of these. T2-weighted sagittal and coronal MR images well clearly showed the location of RNR of the cauda equina; in 16 patients (94%), these were seen above the level of constriction of the spinal canal, and in one case, they were observed below the level of constriction. T2-weighted axial images showed the thecal sac filled with numerous nerve roots. The magnitude of RNR was mild in six cases (35%), moderate in five cases (30%), and severe in six cases (35%). Compared with normal nerve roots, the RNR signal on T2-weighted images was iso-intense. All patients with severe redundancy showed severe LSCS, but not all cases with severe LSCS showed severe redundancy. CONCLUSION: Redundant nerve roots of cauda equina were seen in relatively older patients with moderate or severe LSCS and T2-weighted MR images were accurate in identifying redundancy of nerve roots and evaluating their magnitude and location.

Imaging of the Jaw Cysts with a Dental CT Software Program: Distinction of Odontogenic Keratocysts from Other Cysts

PURPOSE: To evaluate the usefulness of a dental CT software program in the assessment of jaw cysts and in the differentiation of odontogenic keratocysts and other cysts. MATERIALS AND METHODS: Seventeen patients with proven jaw cysts (8 maxillae & 9 mandibles) were evaluated with a dental CT software program for location, locularity, the presence or absence of marginal scalloping, and height to length ratio. For the delineation of involvement or displacement of neurovascular bundles, cortical erosion, perforation or expansion, and tooth root resorption by the jaw cysts, images from this program were compared to conventional images. RESULTS: Seventeen lesions icomprised 15 odontogenic cysts (five odontogenic keratocysts, five radicular, three residual and two dentigerous cysts) and two non-odontogenic cysts (one nasopalatine duct cyst and one postoperative maxillary cyst). Images of jaw cysts obtained with the dental CT software program delineated much more clearly than conventional images the status of neurovascular bundle and cortical bone, but there was no clear difference between the two modalities in delineating tooth root erosion. Dental CT findings of five mandibular odontogenic keratocysts were scalloped margin in all, mandibular ramus involvement in four, height to length ratio below 60% in four, and multilocularity in two. The findings of the other 12 cysts (eight maxillae and four mandibles) were unilocularity in all, smooth inner margin in ten, height to length ratio below 60% in only two, and ramus involvement in none. CONCLUSION: Adental CT software program is an improved imaging modality for assessing jaw cysts ; and findings which tend to indicate odontogenic keratocysts are marginal scalloping, mandibular ramus involvement, prominent spread along the marrow space and multilocularity.

Imaging of Jaw with Dental CT Software Program Normal Anatomy

PURPOSE: Dental CT software program can provide reformatted cross-sectional and panoramic images that cannot be obtained with conventional axial & direct coronal CT scan. The purpose of this study is to describe the method of the technique and to identify the precise anatomy of jaw. MATERIALS AND METHODS:We evaluated 13 mandibles & 7 maxillae of 15 subjects without bony disease who were being considered for endosseous dental implants. Reformatted images obtained by the use of bone algorithm performed on GE HiSpeed Advantage CT scanner were retrospectively reviewed for detailed anatomy of RESULTS: Anatomy related to neurovascular bundle(mandibular foramen, inferior alveolar canal, mental foramen, canal for incisive artery, nutrient canal, lingual foramen and mylohyoid groove), muscular insertion(mylohyoid line, superior & inferior genial tubercle and digastric fossa) and other anatomy(submandibular fossa, sublingual fossa, contour of alveolar process, oblique line, retromolar fossa, temporal crest & retromolar triangle) were well delineated in mandible. In maxilla, anatomy related to neurovascular bundle(greater palatine foramen & groove, nasopalatine canal and incisive foramen) and other anatomy(alveolar process, maxillary sinus & nasal fossa) were also well delineated. CONCLUSION: Reformatted images using dental CT software program provided excellent delineation of the jaw anatomy. Therefore, dental CT noftware program can play an important role in the preoperative assessment of mandible and maxilla for dental implants and other surgical conditions.